Secondary battery

Abstract

To provide a battery cell structure capable of improving heat dissipation without degradation of an energy density and an obstacle to size reduction while an electrode layer of a battery cell has sufficient heat transfer properties. The present invention relates to a cell structure including a positive/negative electrode formed in such a manner that a conductive base member having a three-dimensional structure contains an electrode active material and a collector formed continuously to the positive/negative electrode. One surface of the collector is formed continuously in a longitudinal direction of the positive/negative electrode (across a large area), and the other surface of the collector is exposed in a longitudinal direction of the cell structure (across a large area).

Description

[0001]This application is based on and claims the benefit of priority from Japanese Patent Application 2020-095591 filed on 1 Jun. 2020, the content of which is incorporated herein by reference.BACKGROUND OF THE INVENTIONField of the Invention[0002]The present invention relates to a secondary battery such as a lithium ion battery, and particularly relates to a cell structure of a secondary battery improving heat dissipation in the secondary battery.Related Art[0003]Typically, a lithium ion battery has been widely used as a secondary battery having a high energy density. The secondary battery such as the lithium ion battery includes a cell structure having a collector made of metal foil, a positive / negative electrode configured such that a compounding agent containing an electrode active material is applied to a surface of the collector, and an electrolyte interposed between the positive and negative electrodes.[0004]For developing an effective function and ensuring durability such a...

AI Technical Summary

Benefits of technology

[0014]The secondary battery of the present invention is also applicable to a module configured such that a plurality of secondary batteries is aligned in electrical connection with each other. According to the structure of the collector of the present invention, a bus bar essential for typical module formation is not necessary, and a series design can be achieved by surface contact of both cell surfaces. Thus, a resistance component due to the bus bar can be eliminated, and a low-resistance module design having high heat dissipation can be achieved. Moreover, size and weight reduction can also be achieved.

[0015]In the second battery of the present invention, the conductive base member of the positive / negative electrode is made of foam metal having a three-dimensional structure. The metal foam has the mesh-shaped three-dimensional structure, and has a large surface area. The foam porous body made of the metal is used as the conductive base member of the positive / negative electrode so that the mesh-shaped structure can be filled with an electrode compounding agent containing an electrode active material and an active material amount per unit area of an electrode layer can be increased. In addition, the volumetric energy density of the lithium ion secondary battery can be improved.

[0016]Since the collection tab is not necessary, the present invention can prevent, as additional effects, durability deterioration due to uneven welding at a step welded portion between the collection tab and the exterior body (a laminated film), can reduce liquid leakage and gas leakage due to such durability deterioration, and can improve pressure resistance to internal gas.

[0017]Since the collection tab is not necessary, the present invention can eliminate, as other additional effects, the necessity of taking the width of the collection tab into consideration, and can narrow a width between battery cells. Thus, a design can be freely made from one with a small width to one with a great width. The degree of freedom in the design of the shape of the battery cell is increased so that a battery can be produced in a shape corresponding to an application to be applied.

[0018]As described above, the present invention has an advantageous effect that the heat dissipation can be significantly improved because one surface of the collector is formed continuously in the longitudinal direction of the positive / negative electrode, which is configured such that the conductive base member contains the electrode active material, across the large contact area and the other surface of the collector is exposed in the longitudinal direction of the cell structure across the large area. The present invention produces the above-described additional effects.

Problems solved by technology

For this reason, as long as heat dissipation of the collection tab of the collector is not enhanced, even in the structure for reducing accumulated heat in the electrode layer of the battery cell as in Japanese Unexamined Patent Application, Publication No. 2017-212111, such an effect cannot be sufficiently produced.

In a case where the size of the collection tab is increased for improving the heat dissipation of the collection tab, there are problems that an energy density is degraded and an obstacle to size reduction is caused.

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